Re: Problems getting Cisco router and Motorola Nextlevel system to work together

[Brian Raaen <braaen () zcorum com>]

The buffers are overloading and dropping traffic.  With a Cisco TAC case, the 
tech had me increase the buffers so much it wasn't even funny.  The only 
problem was about and hour after we tried to tune the buffers, things got 
very bad and I had clear them to default to stop a very ugly bigger outage.  
This system does indeed involve IPTV set top boxes.  I am unable to use RBE 
since the PVC provisioning may change on the units and the VC would not match 
what the dhcp lease was originally on.  The way that this Motorola system 
implements PVCs baffles me, it does not make any sense to me.  They are 
dynamically changing the vci assigning it out of a pool, just like DHCP does 
with IPs.  The circuits are not SVCs and the endpoint router is seeing things 
change so this is not SPVCs either.  I am trying to think of a way the change 
this to work with RBE switching, but the dynamic PVCs are throwing a monkey 
wrench into things.  Thank for the help.

-- 
Brian Raaen
Network Engineer
braaen () zcorum com

On Tuesday 24 July 2007 22:58, you wrote:
> We should probably move this over to cisco-nsp.
>
> I'd be interested to see a 'sh buffers' because if it's
> process switching that much data I bet the buffers are thrashing.
>
> I seem to remember working on something very similar to that
> 4 or 5 years ago when a customer has brigding over a bunch of
> ATM PVC's and they told me it was some type of IPTV set top box.
>
> We tuned the buffers really high so they didn't trim back and
> it worked. 
>
> We also do some bridging under interrupt without process 
> switching too last time I checked so some more data would
> be helpful.
>
> Move it over to cisco-nsp () puck nether net and we can help
> more on the Cisco side if you want.
>
> Rodney
>
> On Tue, Jul 24, 2007 at 09:25:49PM +0100, michael.dillon () bt com wrote:
> > >   The router is currently configured to use IRB which is a 
> > > hybrid process.  
> > > The problems is that the IRB process is overloaded and is 
> > > dropping traffic faster than it can process it. 
> >
> > Which NPE is in this router?
> >
> > Basically, the 7200 has underpowered CPUs and if you force it to process
> > switch, then it handles a LOT LESS packets per second than you might
> > think. I expect that your config is forcing process switching rather
> > than fast switching.
> >
> > The only three solutions are
> >
> > A) run less traffic through the 7200 so that process switching can cope
> >
> > B) stop using the feature that forces process switching
> >
> > C) replace the 7200 with a 7300 which will probably not have CPU issues.
> > However, not knowing the specifics of what IRB is doing, I would advise
> > you to test a replacement platform before committing to it.
> >
> > Oh well, maybe 4 solutions. If you are using a weak NPE such as NPE-200
> > you may be able to get some joy by upgrading to a more powerful one. For
> > instance an NPE-400 should handle roughly twice the load of an NPE-200.
> >
> > --Michael Dillon